Studying the Effects of the Loss of Vegetation on the Height of Cardus rectangulatus
Population
The set of cards represent a herbivorous population, Cardus rectangulatus.. You plan to
sample the population each month for four months starting in April. Each month for 3
consecutive nights you trap 6 animals. You measure their height and calculate the
average height of the sample. You then immediately return your animals back into the
environment.
Materials and Procedure
 You will need a deck of cards-four each of the numbers 1 through 10.
1. Draw six cards from the deck. Record the number shown on each card on the data table as
height of organisms.
2. Calculate the average height of samples for the day and record it on the data table.
3. Return the six cards to the deck.
4. Repeat steps 1, 2, and 3 for days two and three.
5. Calculate the average height of your samples for days one, two and three. Record it on the
data table under “average height of the population”
One month later you return to repeat the study. You observe that all the vegetation
below the height of 5 cm has been devoured by a caterpillar infestation. Question 1:
What effect would this have on the population of Cardus rectangulus? Record your
prediction at the top of the data sheet.
6. Remove all the cards with the numbers 1-4 to represent the plants 1-4 cm in height that
were eaten. Shuffle the deck
7. Repeat the procedure steps 1-5
One month later the caterpillars have eaten all vegetation below a height of 7cm.
Question 2: Which organisms would be affected by this loss of food supply? Record your
answer on the data sheet.
8. Remove all the cards with numbers 5-6 to represent the loss of plants 5-6cm in height.
(You should now only have cards with 7-10 on them.) Shuffle the deck.
9. Repeat the procedure steps 1-5.
One month later you return to find the caterpillars have eaten all the vegetation below a
height of 9cm. Question 3: Which organisms would be affected by this loss of food
supply? Record your answer on the data sheet.
10. Remove all the cards with numbers 7-8 and shuffle the deck. (You should now only have
cards with numbers 9 and 10 on them). Shuffle the deck.
11. Repeat the procedure steps 1-5.
12. Graph your data for the average height of plants at the end of each month.
13. Answer the analysis questions.
Name _________________________________________
Class Period ____________________________________
Date _____________
Studying the Effects of the Loss of Vegetation on Cardus rectangulatus Population
Data Sheet
Question 1: Prediction: _______________________________________________________
Question 2: Which organisms would be affected by the loss of food < 7cm in height? ______
__________________________________________________________________________
Question 3: Which organisms would be affected by the loss of food < 9cm in height? ______
__________________________________________________________________________
Data Table –on back
Analysis Questions
4a. Describe how the procedures you used with the cards are similar to the real sampling
techniques used by scientists.
4b. If conditions described in this study remained the same, what adaptations could you
expect from the Cardus rectangulatus population?
4c. Why did the cards with the higher numbers have an advantage over the cards with the
lower numbers?
4d. Is height always an advantage to organisms? Why or why not?
Data Table
Sampling
Date
Sample
Number
1
Average
Height of
Sample
Height of Organism (cm)
2
April
3
X
X
X
X
X
X
X
1
X
X
X
X
X
X
2
3
May
X
X
X
X
X
X
X
1
X
X
X
X
X
X
2
3
June
X
X
X
X
X
X
X
1
X
X
X
X
X
X
2
July
Average
Height of
Population
X
X
X
X
X
X
3
X
X
X
X
X
X
X